A lot of parents I've talked to have made name decisions one at a time -- that is, they chose a first name first, then they chose middle name second (or vice versa). So that's one method you could try -- focusing on just one variable first, then, once you've got that one done, shifting and focusing on the other. This helps keep the process simple, too.
Here are some thoughts on the first names you listed...
Arielle - I like this spelling. The name may prompt people to ask about Ariel the mermaid, but that's the only drawback I can think of.
Kyla - It's nice, though I do think it's a bit cutesy. (I tend to prefer older/traditional names, though, so that's just a bias I have.)
Amelie - I really like this one. It has a cute "feel," like Kyla, but it's a very well-established name. Best of both worlds. This one is my favorite of the bunch.
Adrienne/Adriana - Close second favorite to Amelie. It'll be tough to decide between the French and Spanish forms, though, because both are lovely. Maybe balance out the Spanish surname with a French forename? Hm.
Darien - I'd be concerned about people misspelling it, especially as the spellings Darian and Darion are both more popular, and spellings like Darrian, Darrien and Darrion are also used a lot.
Evan - This one is my favorite. It's more straightforward than Darien and Davin, and it's not a trendy -ayden name (see below).
Hayden - I'm not sure if you have an opinion about trendy names, but Hayden definitely falls into the trendy category (along with all other -ayden names). Some people really like trendy names, but, personally, I'm not a fan.
Davin - My initial reaction was confusion b/c I couldn't figure out if it would be pronounced DAYV-in (like David, but with an N) or DAV-in (like a shortened Davenport).